We are using NT 4.0 + 6.5 + Microfocus Netexpress

After the server is booted, our application flies.

After some days ( 1 to 3), the performance starts to degrade until it reaches an unbearable sluggishness. Teh degradation is not continuous, but it shows with time spans (which vary from 1 to 5 hours) during which everything is unacceptably slow. This time spans are usually longer each time they present themselves. There are no errors and if given the time (unacceptable) every workstation finishes its tasks properly.

If we stop the server and reboot it, everything comes back to the initial excellent performance and the cycle of degradation starts over again.

The hardware is excellent and we have checked almost everything that came into our minds, with no results.

Does anyone have any previous similar experiences ?
Does anyone have any ideas on where we should focus our search ?

We are migrating the application into 7.0 but I am afraid that our nightmares might continue

I would appreciate all the advice you could give me. Thank you

Elias